Undefined symbol "start" while linking D program through LD

Question

I have following simple program:

import std.stdio;

int main(string[] argv) {
    writeln("Hello, world!");

    return 0;
}

I'm building it as follows:

DMD -c -m64 -od/proj/out -w -wi -fPIC -debug \
    -g -I/proj/hello -unittest /proj/hello.d

LD -L/usr/share/dmd/lib/ -arch x86_64 -execute -macosx_version_min 10.7 \
    -pie -lm -lpthread -lphobos2 -o /proj/out/hello_app /proj/out/hello.o

Compilation passes perfectly, but linking stucks with following:

Undefined symbols for architecture x86_64:
  "start", referenced from:
     -u command line option
     (maybe you meant: _D3std9algorithm41__T10startsWithVAyaa6_61203d3d2062TAhTAhZ10startsWithFAhAhZb, _D4core6thread6Thread5startMFZv , _D3std9algorithm91__T10startsWithVAyaa11_62203c20612e74696d6554TAS3std8datetime13PosixTimeZone10TransitionTlZ10startsWithFAS3std8datetime13PosixTimeZone10TransitionlZb , _D3std9algorithm43__T10startsWithVAyaa6_61203d3d2062TAyaTAyaZ10startsWithFAyaAyaZb , _D3std9algorithm41__T10startsWithVAyaa6_61203d3d2062TAxaTaZ10startsWithFAxaaZb , _D3std9algorithm92__T10startsWithVAyaa11_62203c20612e74696d6554TAS3std8datetime13PosixTimeZone10LeapSecondTylZ10startsWithFAS3std8datetime13PosixTimeZone10LeapSecondylZb , _D3std9algorithm92__T10startsWithVAyaa11_62203c20612e74696d6554TAS3std8datetime13PosixTimeZone10TransitionTylZ10startsWithFAS3std8datetime13PosixTimeZone10TransitionylZb )
ld: symbol(s) not found for architecture x86_64

I guess I forgot some additional static library to link with to have it setup everything, but what exactly?

Also I've seen instructions about how to do separate compilation and linking somewhere on dlang site, but cannot find it.

UPD1: When linking with help of GCC using gcc -L/usr/share/dmd/lib/ -lphobos2 -lm -lpthread hello.o, it works, but I need to use ld.

Answer 1

Add -lcrt1.o when linking.

LD -L/usr/share/dmd/lib/ -arch x86_64 -execute -macosx_version_min 10.7 \
  -pie -lm -lpthread -lphobos2 -lcrt1.o -o /proj/out/hello_app /proj/out/hello.o

[update] Ah, you got it : )

Answer 2

Found it due to pure luck!

It should be linked with -lphobos2 -lm -lpthread and -lcrt1.o - then everything links and works fine.